Fuel tank welding joint and manufacturing method thereof

ABSTRACT

A welding joint  10  for a fuel tank reduces the amount of fuel vapor in the fuel tank that escapes into the atmosphere. The fuel tank welding joint  10  a joint main body  20  and a barrier layer laminated on the surface of the joint main body  20.  The joint main body  20  is formed of a first resin material weldable to the wall of the fuel tank FT, and the barrier layer  30  is formed of a second resin material that is adhesively and chemically reactive with the first resin material and that is more fuel-impermeable than the first resin material. An end portion  34  formed so as to be exposed to the outside at the end of a tube portion  24  is formed on the barrier layer  30.  When the barrier layer  30  is injection molded on the surface of the joint main body  20,  the end portion  34  is formed by the flow of the second resin material through the end of the tube portion  24  to increase the adhesive strength of the end face where the parts are joined.

[0001] This application claims the benefit of and priority from JapaneseApplication No. 2001-56806 filed Mar. 1, 20001, the content of which isincorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a welding joint for fuel tanks,which is welded to a tank wall of a fuel tank to provide a connectingpassage between the interior of the fuel tank and the outside.

[0004] 2. Description of the Related Art

[0005] A example of a conventional fuel cut-off valve as a fuel tankwelding joint is disclosed in JP 2000-8981A. FIG. 13 is a crosssectional view of a fuel cut-off valve 100. In FIG. 13, the fuel cut-offvalve 100 comprises a case main body 102 welded to a tank upper wallFTa, a float 112, a spring 114, and a bottom plate 116. A connectingpassage 102 a is opened and closed by the float 112 according to a levelof the fuel in the fuel tank FT. The upper part of the case main body102 serves as a lid 104, which is welded to the tank top wall FTa at anannular welded edge portion 106 of the lid 104. When the fuel tank FT isfueled, causing the fuel level to rise, fuel vapor in the fuel tank FTflows out of a float chamber through the connecting passage 102 a to theoutside. When the fuel reaches a predetermined level FL1 in the fueltank FT, the flotation force of the float 112 in the fuel cut-off valve100 increases, causing the float 102 to rise and close the connectingpassage 102 a, so as to prevent the fuel from flowing out of the fueltank FT.

[0006] The tank upper wall FTa is made of polyethylene, and the lid 104is made of nylon or a polyacetal. The annular welded edge portion 106 ismade of a modified olefinic resin containing a polar functional group,and is thus thermally welded at either end to the lid 104 formed ofnylon and the tank upper wall FTa formed of polyethylene. Specifically,polyethylene and nylon are not miscible with each other, but they canboth be welded by interposing the modified olefinic resin containing apolar functional group.

[0007] In the conventional technology, however, the lid 104 is made ofpolyethylene, and the fuel vapor in the fuel tank FT can thus penetratethrough the lid 104, however slightly, to be released into theatmosphere. Such fuel vapor leaks should be minimized in the interestsof environmental safety.

SUMMARY OF THE INVENTION

[0008] To overcome such drawbacks, an object of the present invention isto provide a fuel cut-off valve permitting less fuel vapor in fuel tanksfrom being released into the atmosphere.

[0009] To solve this problem, an exemplary first embodiment of thepresent invention provides a fuel tank welding joint for connecting afuel tank to a prescribed member. The fuel tank welding joint comprisinga joint main body including a welded edge portion that is configured tobe thermally welded to a wall of the fuel tank and a tube portion forconnecting a hose, the tube portion having a connecting passage toconnect an interior of the fuel tank and the prescribed member and abarrier layer formed on a surface of the joint main body.

[0010] The joint main body is made of a first resin material that isweldable to a wall of the fuel tank, and the barrier layer is made of asecond resin material that is adhesively and chemically reactive withthe first resin material and that is more fuel-impermeable than thefirst resin material, the barrier layer having an end portion formed soas to extend past an end of the tube portion.

[0011] The fuel tank welding joint of the present invention is thermallywelded at the welded edge portion of the joint main body on the wall ofthe fuel tank. The joint main body is formed of a first resin materialthat is weldable to the wall of the fuel tank, and is thus easilythermally welded to the welded edge portion. When the hose is connectedto the tube portion of the joint main body, it is connected to theinterior of the fuel tank through the connecting passage.

[0012] A barrier layer is also formed on the surface of the joint mainbody. The barrier layer is formed of a second resin material that hasbetter fuel impermeability than the first resin material, thus shieldingthe joint main body from the outside and reducing fuel permeation.

[0013] Because the second resin material is also adhesively andchemically reactive with the first resin material, the barrier layer isintegrally formed with the joint main body, leaving no gap between itand the joint main body, so as to further prevent fuel vapor in the fueltank from being released.

[0014] The joint main body also has the following structure to improvethe adhesive strength at the end face where it is joined to the barrierlayer.

[0015] Specifically, when the fuel tank welding joint is produced, thejoint main body is formed with the first resin material, and the barrierlayer is then formed with the second resin material by means ofinjection molding on the surface of the joint main body. When thebarrier layer is injection molded, the second resin material flowsthrough the end of the tube portion of the joint main body and fills theend portion-forming cavity to form the end portion. At that time, theend face where the end portion and the end of the tube portion arejoined does not serve as the end for the flow of the second resinmaterial, which fuses at a high temperature, thus affording a highdegree of adhesive strength.

[0016] The second resin material flows through the narrow end of thetube portion during the injection molding of the barrier layer,resulting in shearing heat. The shearing heat keeps the second resinmaterial at a high temperature to ensure better adhesion with the firstresin material. The barrier layer is thus joined with considerableadhesive force to the end of the tube portion, with little danger ofseparation from the tube portion.

[0017] Thus, when the first resin material has greater fuelexpandability than the second resin material, the joint main body isexpanded by the fuel in the fuel tank more than the barrier layer, yetwill not separate.

[0018] In a preferred embodiment of the first invention, the fuel tankis formed of polyethylene, where the first resin material is a modifiedolefinic resin containing a polar functional group, and the second resinmaterial is a polyamide or polyacetal. The olefinic resin can be weldedbecause it is the same type of resin as polyethylene, and because apolar functional group has been added, it reacts and adheres topolyamides or polyacetals.

[0019] The second invention is a method for producing a fuel tankwelding joint for connecting a fuel tank to the outside. The fuel tankwelding joint comprises a first step of forming a joint main body with afirst resin material and a second step of feeding a second resinmaterial into a mold cavity in which the joint main body has been set,so as to form a barrier layer. The second step comprises the step ofallowing the second resin material to flow through the end of the tubeportion into the cavity to form the end portion.

[0020] In a preferred embodiment of the second invention, the mold unitcomprises a split mold comprising a first mold and second mold. Thejoint main body comprises a burr cutting edge upstream from the weldededge portion in the route through which the resin material passes, theburr cutting edge being pressed to the second mold by the clampingpressure from the first mold to define the cavity.

[0021] When the joint main body is set in the first and second molds andis clamped, the burr cutting edge of the joint main body is pressed intothe second mold by the clamping pressure of the first mold to define thecavity. Because the burr cutting edge is formed upstream in the routethrough which the resin flows to the welded edge portion, the cavity isdefined in order to prevent the resin from flowing to the welded edgeportion. Accordingly, no second resin material that is not welded to thefuel tank reaches the vicinity of the welded edge portion, thus ensuringthat the fuel tank welding joint is always welded to the fuel tank atthe welded edge portion.

[0022] Because the burr cutting edge is directly subject to the clampingforce between the first and second molds, dimensional imperfectionsresulting from resin contraction and the like during the manufacture ofthe joint main body are absorbed so as to prevent gaps from beingcreated at the end of the cavity, thus ensuring that resins leaks willbe prevented.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023]FIG. 1 is a cross sectional view illustrating a fuel tank weldingjoint attached to the top of an automobile fuel tank in a firstembodiment of the present invention;

[0024]FIG. 2 is a cross sectional view illustrating the fuel tankwelding joint before it is welded to the fuel tank;

[0025]FIG. 3 illustrates a mold used in the injection molding step;

[0026]FIG. 4 illustrates a mold used in the step subsequent to FIG. 3;

[0027]FIG. 5 illustrates the flow of resin in the injection moldingstep;

[0028]FIG. 6 illustrates the flow of resin in the injection moldingstep;

[0029]FIG. 7 is a cross sectional view illustrating the top of a fuelcut-off valve in a second embodiment;

[0030]FIG. 8 is a detail cross sectional view of the vicinity of the endof the lid (welding joint) in FIG. 7;

[0031]FIG. 9 shows a cross sectional view as a modification of thesecond embodiment;

[0032]FIG. 10 is a detail cross sectional view of the vicinity of theend of the lid (welding joint) in FIG. 9;

[0033]FIG. 11 is a cross sectional view illustrating anothermodification of FIG. 10;

[0034]FIG. 12 illustrates a modification of the burr cutting edge inanother embodiment; and

[0035]FIG. 13 is a cross sectional view of a conventional fuel cut-offvalve.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036]FIG. 1 is a cross sectional view illustrating a fuel tank weldingjoint 10 attached to an upper wall of an automobile fuel tank FT in afirst embodiment of the present invention. In FIG. 1, the fuel tank FTis formed by blow molding in three layers using composite resinmaterial, with polyethylene. Specifically, the fuel tank FT comprisesthe lamination of a tank inner layer FT1, a tank outer layer FT2, and abarrier layer FT3 interposed between the tank inner layer FT1 and tankouter layer FT2. The tank inner layer FT1 and tank outer layer FT2 areformed of a high density polyethylene, and primarily function asstructural components to ensure the mechanical strength of the fueltank. Meanwhile, the barrier layer FT3 is formed of ethylene vinylalcohol (EVOH) or a polyamide (PA) characterized by exceptional fuelvapor impermeability, and functions as a blocker to prevent fuel vaporfrom penetrating through.

[0037] The fuel tank welding joint 10 is a joint that covers theattachment port FTc of the fuel tank FT and connects to a hose H, andcomprises a joint main body 20 and a barrier layer 30 laminated to asurface of the joint main body 20.

[0038]FIG. 2 is a cross sectional view of the fuel tank welding joint 10before the fuel tank welding joint 10 is welded to the fuel tank FT. InFIG. 2, the joint main body 20 comprises a stop plate 22, a flange 26formed around the circumference of the stop plate 22 and a tube portion24 for attaching the hose, the tube portion 24 having a connectingpassage 20 a connecting the interior of the fuel tank FT with theoutside. Formed on a bottom end of the flange 26 is an annular weldededge portion 26 a that is welded to the tank upper wall FTa of the fueltank FT.

[0039] The barrier layer 30 covers a wide area on the surface of thejoint main body 20 with a resin material having exceptional fuel vaporimpermeability so as to reduce penetration by fuel vapor. The barrierlayer 30 comprises the inner tube layer 32 formed along the connectingpassage 20 a of the joint main body 20, the end portion 34 formed so asto be externally exposed at the end of the tube portion 24 and theumbrella-shaped portion 36 formed on the inner wall of the flange 26,which are integrally formed.

[0040] The end portion 34 is formed by the flow of the resin through theend of the tube portion 24 when the barrier layer 30 is injection moldedon the surface of the joint main body 20. The step for the injectionmolding of the barrier layer 30 is described below.

[0041] The resin materials for forming the joint main body 20 andbarrier layer 30 should be determined in consideration of theweldability with the fuel tank FT, the fuel vapor impermeability, theadhesion between the joint main body 20 and barrier layer 30, and soforth.

[0042] Specifically, the resin for the joint main body 20 is determinedin consideration primarily of the thermal weldability to the fuel tankFT. When the tank outer layer FT2 of the fuel tank FT is made ofpolyethylene, a modified olefinic resin (first resin material)containing a polar functional group is used for the joint main body 20.

[0043] The resin for the barrier layer 30 is determined in considerationprimarily of the fuel vapor impermeability. A polyamide or polyacetal(second resin material) is used for the barrier layer 30.

[0044] Since the first resin material forming the joint main body 20 isan olefinic resin, the first resin material can be welded to the similarpolyethylene forming the tank outer layer FT2, and since the first resinmaterial contains a polar functional group, the first resin materialreacts and adheres to the polyamide or polyacetal forming the barrierlayer 30.

[0045] The welding of the fuel tank welding joint 10 to the tank upperwall FTa of the fuel tank FT is described below. In FIG. 2, the bottomend of the welded edge portion 26 a of the fuel tank welding joint 10 isfused by means of a hot plate (not shown in figure), and the area aroundthe attachment port FTc of the fuel tank FT is fused by a hot plate (notshown), resulting in a welded portion FTd. The welded edge portion 26 ais pressed to the welded portion FTd. As a result, the welded edgeportion 26 a and the welded portion FTd are both formed of an olefinicresin material, and are thus welded together when cooled tosolidification.

[0046] While these part are in this state, as illustrated in FIG. 1, thehose H is fitted to the tube portion 24 of the joint main body 20 andclamped with a clamp CP, and the hose is thus connected to the interiorof the fuel tank FT by way of the connecting passage 20 a. At that time,the end face 20 b joining the end of the tube portion 24 of the jointmain body 20 to the end portion of the barrier layer 30 will be coveredby the inside of the hose H to provide a seal against the outside.

[0047] The barrier layer 30 is formed of the second resin material whichis more fuel vapor impermeable than the first resin material, thusshielding the joint main body 20 from the outside to reduce the amountof fuel permeation. Since the second resin material is also adhesivelyand chemically reactive with the first resin material, the barrier layer30 is integrally formed with the joint main body 20, leaving no gapsbetween the barrier layer 30 and the joint main body 20, so as tofurther prevent the fuel vapor inside the fuel tank from escaping intothe atmosphere.

[0048] A method for producing the fuel tank welding joint 10 isdescribed below. The fuel tank welding joint 10 is formed by what isreferred to as two-color molding. Two-color molding is a method in whichthe joint main body 20 and barrier layer 30 are integrally formed uponthe separate injection molding of two types of resins.

[0049]FIGS. 3 and 4 illustrate the molds which are used in two stagesduring the steps for producing the fuel tank welding joint. In thisstep, two molds 50 are changed over in sequence, and the first resinmaterial and second resin material are injected from different injectionmolding machines.

[0050] In FIG. 3, the mold 50 comprises a first mold 52, second mold 53,and third mold 54, where a first cavity 56 is formed while surrounded bythe first mold 52, second mold 53, and third mold 54. A gate 57connected to the injection molding machine is formed in the first cavity56. While the mold 50 is clamped, the first resin material is injectedthrough the gate 57 to form the joint main body 20 (see FIG. 1). Thefirst mold 52 and third mold 54 are then opened relative to the secondmold 53.

[0051] Then, as shown in FIG. 4, the joint main body 20 formed in thefirst step is clamped by the fourth mold 55 and fifth mold 58 whilemounted in the second mold 53. The fourth mold 55 and fifth mold 58 forma second cavity 59 with the joint main body 20. Specifically, the shapeof the second cavity 59 conforms to the barrier layer 30 (FIG. 1). Agate 61 connected to the injection molding machine is connected to thesecond cavity 59. The molds are opened in the direction indicated by thearrows in the figure to take out the final product.

[0052]FIG. 5 is a detail of the area around the bottom of the secondcavity 59 in FIG. 4. In FIG. 5, the burr cutting edge 28 is formed instages upstream from the welded edge portion 26 a of the joint main body20 while the fourth mold 55 and fifth mold 58 are clamped to the secondmold 53. The burr cutting edge 28 is pressed to the fifth mold 58 by theclamping pressure from the second mold 53, defining the second cavity59.

[0053] When the second resin material R2 is injection molded through thegate 61 while the mold is thus clamped, the second cavity 59 is filled.At that time, as shown in FIG. 6, the second resin material R2 flowsthrough the end of the tube portion 24 of the joint main body 20, andfills the cavity to form the end portion 34. The end face 20 b where theend portion 34 and the end of the tube portion 24 are joined does notdispose in the end for the flow of the second resin material R2, and thesecond resin material R2 is welded at a high temperature to the jointmain body 20, thus affording a high degree of adhesive strength.

[0054] The second resin material R2 flows through the narrow end of thetube portion 24 during the injection molding of the barrier layer 30,resulting in shearing heat. The shearing heat keeps the second resinmaterial R2 at a high temperature, melting the surface of the joint mainbody 20 to ensure better adhesion with the first resin material. Theinjection temperature of the second resin material R2 is 250 to 300° C.,which is higher than the injection temperature of 200 to 230° C. of thefirst resin material. The resin thus flows to subsequent steps at a hightemperature, ensuring better adhesive chemical reaction.

[0055] The barrier layer 30 is thus joined with considerable adhesiveforce to the end face 20 b disposed to the end of the tube portion 24,with little danger of separation from the tube portion 24.

[0056] The first resin material thus has greater fuel expandability thanthe second resin material, and the joint main body 20 is expanded by thefuel in the fuel tank more than the barrier layer 30, yet will notseparate from the barrier layer 30.

[0057] As shown in FIG. 5, the joint main body 20 is provided with aburr cutting edge 28, resulting in the following action. Specifically,when the mold is clamped with the joint main body 20 set up in thesecond mold 53 and fifth mold 58, the burr cutting edge 28 of the jointmain body 20 is pressed to the fifth mold 58 by the clamping force ofthe second mold 53, thus defining the second cavity 59. Because the burrcutting edge 28 is formed upstream in the route through which the secondresin material R2 flows to the welded edge portion 26 a, the secondcavity 59 is defined to prevent the resin from flowing to the weldededge portion 26 a. As such, no second resin material R2 that is notwelded to the fuel tank FT reaches the area around the welded edgeportion 26 a, thus ensuring that the fuel tank welding joint 10 iswelded to the wall of the fuel tank at the welded edge portion 26 a.

[0058] Furthermore, since the burr cutting edge 28 is directly subjectto the clamping force between the second mold 53 and fifth mold 58,dimensional imperfections resulting from resin contraction during themanufacture of the joint main body 20 are absorbed to prevent gaps frombeing created at the end of the second cavity 59, thus ensuring thatresins leaks will be prevented.

[0059]FIG. 7 is a cross sectional view of the top of a fuel cut-offvalve 70 in a second embodiment. The second embodiment is characterizedby a structure in which the fuel tank welding joint is used for a fuelcut-off valve 70. In FIG. 7, the fuel cut-off valve 70 comprises a lid72 forming the welding joint mounted on the tank upper wall FTa, a casemain body 80, a float 82, a spring, and a bottom plate, where aconnecting passage 72 a is opened and closed by the float 82 accordingto the level of fuel in the fuel tank FT. The lid 72 comprises a lidmain body 74 (joint main body) and a barrier layer 76, which arelaminated. The barrier layer 76 is formed along the outer wall of thelid main body 74. As illustrated in FIG. 8, the second resin materialflows through the end of the lid main body 74 to form the end portion 73during the injection molding of the barrier layer 76, thus improving theadhesive strength at the end face 72 c where the parts are joined.

[0060] As shown in FIG. 9, which illustrates another modification of afuel cut-off valve, a barrier layer 76B may be formed on the innersurface of a lid main body 74B forming a fuel cut-off valve 70B. Thismodification, as illustrated in FIG. 10, can improve the adhesivestrength at an end face 72Bc to which the lid main body 74B is joined,during the formation of the barrier layer 76B.

[0061] Furthermore, as illustrated in the modification in FIG. 11, whena leading end face 74Ca of a lid main body 74C is covered by an endportion 73C extending out from a barrier layer 76C, the adhesivestrength of the joining welded face 72Cc can be even further improved,making this a preferred option.

[0062] The present invention is not limited to the above embodiments.Various embodiments can be worked within the scope of the invention.Examples are given below.

[0063] (1) In the embodiment illustrated in FIG. 5, the burr cuttingedge 28 is formed as a step, resulting in a shape which presses at rightangles onto the flat surface of the fifth mold 58, but this is not theonly option, and the part may be in the form of a tapered surface asillustrated in FIG. 12. That is, a burr cutting edge 28D has a taperedform with an angle α° (10°) or more, so that the flow of the secondresin material R2 to the welded edge portion 26Da side is cut off by theclamping pressure in the upward diagonal direction of the fifth mold58D, eliminating burs.

[0064] (2) Various types of joints may be used, provided that the fueltank is connected to the outside. For example, joints to inlet pipes forsupplying fuel can be used.

[0065] The foregoing detailed description of the invention has beenprovided for the purpose of explaining the principles of the inventionand its practical application, thereby enabling others skilled in theart to understand the invention for various embodiments and with variousmodifications as are suited to the particular use contemplated. Theforegoing detailed description is not intended to be exhaustive or tolimit the invention to the precise embodiments disclosed. Modificationsand equivalents will be apparent to practitioners skilled in this artand are encompassed within the spirit and scope of the appended claims.

What is claimed is:
 1. A fuel tank welding joint for connecting a fueltank to a prescribed member, the fuel tank welding joint comprising: ajoint main body including (i) a welded edge portion that is configuredto be thermally welded to a wall of the fuel tank and (ii) a tubeportion for connecting a hose, the tube portion having a connectingpassage to connect an interior of the fuel tank and the prescribedmember; and a barrier layer formed on a surface of the joint main body,wherein the joint main body is made of a first resin material that isweldable to a wall of the fuel tank, and the barrier layer is made of asecond resin material that is adhesively and chemically reactive withthe first resin material and that is more fuel-impermeable than thefirst resin material, the barrier layer having an end portion formed soas to extend past an end of the tube portion.
 2. The fuel tank weldingjoint according to claim 1, wherein the barrier layer is formed on thesurface of the joint main body along the connecting passage.
 3. The fueltank welding joint according to claim 2, wherein the end portioncomprises a hose catch for holding the hose, the hose catch having agreater diameter than an outer circumference of the end of the tubeportion.
 4. The fuel tank welding joint according to claim 3, whereinthe barrier layer comprises an umbrella-shaped portion that engages withthe joint main body.
 5. The fuel tank welding joint according to claim1, wherein the first resin material is a modified olefinic resincontaining a polar functional group and the second resin material isselected from the group of polyamide and polyacetal.
 6. A method formanufacturing a fuel tank welding joint for connecting a fuel tank to aprescribed member, the method comprising: a first step of forming ajoint main body made of a first resin material that is configured to bewelded to a wall of the fuel tank, the joint main body including (i) awelded edge portion to be thermally welded to the wall of the fuel tankand (ii) a tube portion for connecting a hose, the tube portion having aconnecting passage to connect an interior of the fuel tank and theprescribed member; and a second step of forming a barrier layer byinjecting a second resin material into a cavity of a mold unit in whichthe joint main body has been set, the second resin material beingadhesively and chemically reactive with the first resin material andmore fuel-impermeable than the first resin material, wherein the secondstep comprises a step of allowing the second resin material to flowthrough an end of the tube portion into the cavity, so as to form an endportion.
 7. The method for manufacturing a fuel tank welding jointaccording to claim 6, wherein the barrier layer is formed on a surfaceof the joint main body along the connecting passage.
 8. The method formanufacturing a fuel tank welding joint according to claim 7, whereinthe end portion comprises a hose catch for holding the hose, the hosecatch having a greater diameter than an outer circumference of the endof the tube portion.
 9. The method for manufacturing a fuel tank weldingjoint according to claim 8, wherein the barrier layer comprises anumbrella-shaped portion that engages with the joint main body.
 10. Themethod for manufacturing a fuel tank welding joint according to claim 6,wherein the first resin material is a modified olefinic resin containinga polar functional group and the second resin material is selected fromthe group of polyamide and polyacetal.
 11. The method for manufacturinga fuel tank welding joint according to claim 6, wherein the mold unitcomprises a split mold including a first mold and second mold; and thejoint main body comprises a burr cutting edge, the burr cutting beingdisposed upstream from the welded edge portion in a route through whichthe second resin material passes, the burr cutting edge being pressed toa part of the second mold by the clamping pressure from the first mold,thereby defining the cavity.
 12. A fuel cut-off valve that opens andcloses a connecting passage, which connects a fuel tank to a prescribedmember, according to a level of fuel in the fuel tank, the fuel cut-offvalve comprising: a lid including (i) a lid main body with theconnecting passage, (ii) a welded edge portion to be thermally welded toa wall of the fuel tank and (iii) a barrier layer formed on a surface ofthe lid main body; a case main body which is mounted on the lid, thecasing main body having a valve chamber connected to the connectingpassage; and a float which is accommodated in the valve chamber, thefloat rising and falling according to a level of fuel in the fuel tank,wherein the lid main body is made of a first resin material that isweldable to a wall of the fuel tank, and the barrier layer is made of asecond resin material that is adhesively and chemically reactive withthe first resin material and that is more fuel-impermeable than thefirst resin material, the barrier layer having an end portion formed soas to extend past an end of the lid.
 13. The fuel cut-off valveaccording to claim 12, wherein the barrier layer is formed on thesurface of the lid main body along the connecting passage.
 14. The afuel cut-off valve according to claim 13, wherein the end portioncomprises a hose catch for holding the hose, the hose catch having agreater diameter than an outer circumference of the end of a tubeportion of the lid main body.
 15. A method for manufacturing a fuelcut-off valve that opens and closes a connecting passage, which connectsa fuel tank to a prescribed member, according to a level of fuel in thefuel tank, the method comprising: a first step of forming a lid made ofa first resin material that is configured to be thermally welded to awall of the fuel tank, the lid including (i) a lid main body with theconnecting passage, (ii) a welded edge portion to be thermal weldable toa wall of the fuel tank and (iii) a barrier layer formed on a surface ofthe lid main body; a second step of forming a barrier layer by injectinga second resin material into a cavity of a mold unit in which the lidmain body has been set, the second resin material being adhesively andchemically reactive with the first resin material and morefuel-impermeable than the first resin material, wherein the second stepcomprises a step of allowing the second resin material to flow throughan end of the lid main body into the cavity, so as to form an endportion.
 16. The method for manufacturing a fuel cut-off valve accordingto claim 15, wherein the barrier layer is formed on a surface of the lidmain body along the connecting passage.
 17. The method for manufacturinga fuel cut-off valve according to claim 16, wherein the end portioncomprises a hose catch for holding the hose, the hose catch having agreater diameter than an outer circumference of the end of a tubeportion of the lid main body.
 18. The method for manufacturing a fuelcut-off valve according to claim 17, wherein the barrier layer comprisesan umbrella-shaped portion that engages with the lid main body.
 19. Themethod for manufacturing a fuel cut-off valve according to claim 15,wherein the first resin material is a modified olefinic resin containinga polar functional group and the second resin material is selected fromthe group of polyamide and polyacetal.
 20. The method for manufacturinga fuel cut-off valve according to claim 15, wherein the mold unitcomprises a split mold including a first mold and second mold; and thelid main body comprises a burr cutting edge, the burr cutting beingdisposed upstream from the welded end in a route through which the resinmaterial passes, the burr cutting edge being pressed to a part of thesecond mold by the clamping pressure from the first mold, therebydefining the cavity to form the end portion.